c++ 求两个数之和，并用cout打印出来

可以使用加法运算符 `+` 来实现求两个数之和，然后使用 `cout` 将结果打印出来。示例代码如下：

#include <iostream>

int main() {
    int a = 5;
    int b = 7;
    int sum = a + b;
    std::cout << "The sum of " << a << " and " << b << " is " << sum << std::endl;
    return 0;
}

输出结果为：

The sum of 5 and 7 is 12